Sewing machine



June 6, 1939. A. H. E VOE' SEWING- MACHINE Filed March 18, 1958 6 Sheets-Sheet 1 J15; ma;

A. H. DE voE sawma MACHINE June 6, 1939.

6 Sheets-Sheet '2 Filed March 18, 1958 l w euk A. H. DE VOE SEWING MACHINE Juhe 6, 1939.

6 Sheets-Sheet 3 Filed March 18, 1938 .9106 Joe fllbert A. H DE VOE SEWING MACHINE June 6, 1939.

6 Sheets-Sheet 4 Y Filed March 18, 1938 211111011101 fllfiert Jffie V09 W Wweom June 6, 1939. A. H. DE VOE 2,161,140

SEWING MACHINE Filed March l8, 1938 6 Sheets-Sheet 5 Show;

A. H DE VOE June 6, 1939.

SEWING MACHINE Filed March 18, 1938 6 Sheets-Sheet 6 Wifnedd:

Patented June 6, 1939 PATENT OFFICE SEWING MACHINE Albert R. De Voe', Livingston Manor, N. Y., as-

signor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application March 18,

23 Claims.

This invention relates to sewing machines, more particularly of the two-thread chain-stitch type having a reciprocatory eye-pointed needle and a complementary thread-carrying looper.

The invention'has for an object to provide a machine of this character with mechanism to sever the under or looper thread periodically without stopping the machine, so that the resultant seam will comprise an uninterrupted needlethread, the work penetrative loops of which are keyed by loops of a looper-thread which is periodically interrupted or severed, resulting in a seam having a series of lengths of looper-thread in end-on relation in the seam.

The looper-thread severing mechanism is so contrived as to sever the looper-thread at points such that the last loop of each length of looperthread of the seam is locked by the finishing end of such length of looper-thread which projects through the needle-thread loop embraced by said last looper-thread loop. Thus each length of looper-thread of the seam is locked against ready r'avelling. In the event that ravelling of the looper-thread should occur for any cause, it can only continue for a few stitches or back as far as a point of interruption of the looper-thread. The provision safeguards the entire seam against being readily ravelled.

Another object of the invention is to provide the machine with a simplified and improved looper-mechanism which is capable of extremely high speeds of operation.

Another object of the invention is to provide the machine with a high-speed-responsive thread-controlling mechanism for the looperthread.

Still another object of the invention is to provide the machine with improved driving mechanism whereby it may be operated at high speeds from the conventional power-transmitters used on the power tables in garment manufacturing establishments, without the necessity of fitting the driving devices on the power-tables with inordinately large driving pulleys.

A still further object of the invention is to provide the machine with a main shaft which is so journaled as to avoid excessive bearing wear caused by the pull of the driving belt which runs from the machine to the usual power-transmitter below the top of the power-table on which the. machine is stationed for use.

With' the above and other objects "in view, as will hereinafter appear, the invention comprises the, devices, combinations, and arrangements of parts hereinafter set forth and illustrated in the 1938, Serial No. 196,641 (Cl. 11219'l) accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the accompanying drawings, Fig. 1 is a side elevation of a sewing machine embodying the invention. Fig. 2 is a plan view of the machine bed and mechanism disposed therein. Fig. 3 r is a section on the line 3-3, Fig. 2. Fig. 4 is a 10 section on the line 44, Fig. 2. Fig. 5 is an end elevation of the clutch-operating means at the left end of the thread-cutter or rear shaft in the machine bed. Fig. 6 is a transverse vertical section through the machine bed adjacent the looper-mec'hanism. Fig. 7 is a perspective view of the thread-cutter mechanism. Figs. 8, 9, 10 and 11 are perspective views of the needle, looper and thread-cutter implements in their cooperative relationships during a thread-cutting operation. Fig. 12 is a plan view of the looper-actuating mechanism. Figs. 13, 14 and 15 are transverse vertical sections on the lines I3I3, l4- and l5-t5, Fig. 2, showing the looper-thread take-up,

i nipper and pull-off devices, respectively. Fig. 16 is a bottom plan view of a portion of the seam produced by the machine. Fig. 1'7 is a side elevation of the seam. Fig. 18 is a bottom plan view of the seam on a smaller scale than that shown in Fig. 16. Fig. 19 is a section on the line l9 l9, Fig. 2. Fig. 20 is a fragmentary plan view of the thread-cutter actuating mechanism in its thrownout or inactive position. Fig. 21 is a disassembled perspective view of the looper and looper-carrier. Fig. 22 is a plan view of the thread-cutter controlling cam. Fig. 23 is a section on the line 23-23, Fig. 2. .Fig'. 24 is a perspective view of one of the three similar sleeves carryingthe coiled spring shanks of the looper-thread controlling arms shown in Figs. 2, 13, 14 and 15. Fig.25 is a plan view of the work-feeding mechanism. Fig. 26 is a side elevation of the feed-bar and associated parts-below the cloth-plate. Fig. 27 is a perspective view of the feed-bar and feed-dog, and Fig. 28 is a section on the line 2828, Fig. 26.

The machine frame comprises a hollow trough-like bed I from a platform or flat surface 2 at one end of which rises the hollow standard 3 of the gooseneck [terminating in the head 5 carrying the reciprocatory eye-pointed needle 6 which is driven by suitable connections from the upper or needle-driving shaft 1 extending horizontally lengthwise of the overhanging gooseneck 4, being journaled in the bearing bushings 8 and 9 in the gooseneck.

The top or needle-driving shaft 1 is connected by the conventional clip-belt I to the main shaft II which is journaled in the bushings I2 and I3 in the hollow standard 3 and carries the twingrooved belt-pulley 4 and balance-wheel l5. It will be observed that, contrary to the usual practice. the belt-pulley I4 is entirely separate from the balance-wheel l5 and is located within the hollow standard 3 between the bearing bushings I2 and I3; the balance-wheel l5, only, being carried by the outboard projection of the main shaft. By these means the strain of the driving belt or belts I6 is applied to the main shaft between its bearings and not to the outboard projection of the main shaft, as heretofore. Longer bearing life and improved operation of theparts are thus attained. The clip-belt It) runs over the pulleys l1 and I8. on the needle-driving shaft 1 and main shafts II, respectively; the pulley |8 being double the diameter of the pulley I1, so that the needledriving shaft 1 runs at twice the speed of the main shaft Journaled in the bed I, in parallel relationship below the level of the main shaft II, are thetwo bottom shafts" l9 and 28 carrying the pulleys 2| and 22, respectively, which are connected by conventional clip-belts 23 and 24 to the respective driving pulleys 25 and 26 on the main shaft H.

The pulleys 25 and 26 are double the diameter of the pulleys 2| and 22, so that the lower shafts I9 and 29 are each driven at twice the speed of the main shaft H or at the same speed as the needle-driving shaft 1.

Cooperating with the. needle 6 in the formation of stitches is the thread-carrying looper 21, Fig. 21, the shank 28 of which has a pivot-hole 28 entered by a cross-pin 29 fixed thereto and jour- -nal'edin bearings 29 in the loopere-carrier 30 which rocks on the aligned pins 3| fixed in lugs 32 in the bed I. The lower shaft 20 carries an eccentric 33 embraced by the follower-sleeve 34 fast on the thin plate-like lever 35 which is .supported at its forward end upon the upper end of ,the upstanding leaf-spring 36 screwed at its lower end to the bed I. The lever 35 carries at its rearward end the cylindrical actuating pin 31 which enters an actuating hole 38 in the looper-shank 28 offset to one side of the axis of the looper-fulcrum pins 29. The hole 38 is slight- 1y hour-glass shaped, as shown in Fig. 12, to permit freedom of motion of the pin 31 therein, without lost-motion or jamming. Thus, the eccentric 33 and lever 35 impart to the looper 21 its endwise or needle-loop-seizing and -shedding movements.

The usual side-throw movements are imparted to the looper by means of the thin link 39, Fig. 6, which is pivotally connected at its forward end to a bracket 48 having a screw-and-slot adjustable connection with the forward end of the thin lever 35. The link 39 is pivotally connected at its rearward end to the looper-carrier 38 and rocks the latter upon its fulcrum-pins 3|. The resultant movement of the looper is the usual elliptical movement commonly performed by.

thread-carrying loopers in the two-thread chainstitch sewing machine art. The single eccentric 33 imparts to the looper 21 all of its operative movements through the mechanism described seizing stroke, and prevent the bowing out of the,

needle-thread on the wrong side of the needle as the latter rises to present its loop for entry by the advancing looper.

The looper-thread cutter comprises a stationary ledger-blade 4| having a shear-cutting edge 42 and a supporting shank 43 which is mounted in the block 44 fixed in the machine bed C0- operating with the ledger-blade is the active blade 45 having a pilot nose 46 and a shearcutting edge 41 at one side of said nose. The blade 45 is mounted in the grooved head 48 of a vertical rock-shaft 49, Fig. '1, journaled in the vertically spaced arms 58 of the block 44 which carries the ledger-blade 4|. shaft 49 is a crank-arm 5| which is connected by the link 52 to the arm 53 of a bell-crank lever 53, 54- fulcrumed on the stud-pin 55 fixed Fixed to the rock in the block 44. The bell-crank arm 54 is formed I with a cam-follower nose 56 which bears upon the cam 51 fast to the worm-gear 58 joumaled on the stud-pin 59. A spring-pressed conical plunger-head 60, housed in a hole in the block 44, bears against a shoulder 6| on the lever-arm 54 to hold the nose 56 against the cam 51 at all times.

Meshing with the worm-gear 58 is the worm 62 formed on the sleeve 63 freelymounted upon the shaft I 9, see Fig. 4. The sleeve 63 is formed at one end with a collar 64 having a clutch-notch 65 which is entered at times by the clutch-pin 66 secured to the head 61 of a pin 68 which may be slid endwise of and within the hole 69 formed axially of and within the shaft l9. The clutchpin 66 slides in a hole in a collar 10, Fig. 4, fast on the shaft l9. The slide-pin 68 is formed at its outward free end with a grooved head 1| which receives the forked end .12, 12 of a clutchcontrolling lever-arm 13 fulcrumed at 14 in the bed I. The lever-arm 13 is rigid with the block 15, Fig. 2, having a flat face 16 which is pressed upon by the looped end 11, Fig. 19, of a stiff wire spring 18 slidable e'ndwise in the bed I and having at one end an upstanding finger-piece 19 by which it may be manipulated to throw the automatic thread-cutter mechanism into or out of operation.

The wire spring 18 is backed adjacent the block 15 by the flat wall 80 in the bed I and, in the position shown in Fig. 2, presses upon the block 15, at the left of the fulcrum 14, thereby urging the slide-pin 68 to the right and causing the clutch-pin 66 to enter the notch 65 in the collar 64 of the worm 62 and couple the worm- 62 to the drive-shaft l9. By sliding the fingerpiece 19 to the other end of its clearance slot 8| in the bed-plate 82, the looped end 80 of the spring 18 is shifted to the right of the fulcrum 14 of the block 15, or to the position shown in Fig. 20 and the clutch-operating arm 13 is moved in a direction to withdraw the clutch-pin 66 from the notch 65 and disconnect the worm 62 from its drive-shaft. In this position of the parts,

the curved freeend 83 of the spring 18 rides upon the forwardly offset bed-shoulder 84 and causes the looped end 11 of. the spring wire to move the block 15 to the throw-out, position shown in Fig. 20.

The cam 51, I portion 85 which holds the thread-cutter blade in retracted position during the sewing of a predetermined number of stitches. At the end of the concentric portion 85 is a slight drop-ofl Fig. 22, has a long concentric shoulder 85' which is timed to allow the threadcutter to move from the position shown in Fig. 8 to the position shown in Fig. 9 wherein the pilot nose enters the looper-thread loop 86 and detains the latter; the cutting edges 42, 41 remaining open. Following the drop-ofi shoulder 85' is a short concentric portion 81, Fig. 22, which detains the thread-cutter parts in the-partly closed position shown in Fig. 10 until another stitch is made by the needle 6." Following the short concentric cam-portion 81 is a second dropoff shoulder 88 which permits the thread-cutter to move to its fully closed position, Fig. 11, to sever the detained looper-thread loop 86. Following the second drop-off shoulder 88 is the cam rise 89 which opens the thread-cutter blade from the position shown in Fig. 11 to the initial position shown in Fig. 8.

The pivoted block I5 has secured to it a stiff wire arm 98"the free end portion of which is doubled back upon the body of the wire to form a shoulder 9|, Fig. 4, and a side face 92, Fig. 2. The thread-cutter actuating lever 54 has a stifi wire extension 93 which terminates in the region of the shoulder 9I and side face 92. The block I5 also has fixed to it a wire brake-arm 94 which, in the thrown-out position of, the parts shown in Fig. 20 engages the groove 95 in the collar of the worm 62 and holds the latter from turning with the shaft I9. In this position of the parts, the extension 93 of the lever 54 is locked by the shoulder 9| against movement in a direction to close the thread-cutter blade 45. It will be observed that, in the thrown-in position of the parts, Fig. 2, the shoulder 9I is outside of. the range of motion of the.free end of the extension 93, so that the lever 54 is free to follow the cam 51. When, however, the cam-follower nose 56 of the lever 54 enters a low point in .the cam 51, Fig. 2, the free end of the wire extension 93 of the lever 54 moves in front of the side face 92 of the arm 98 and the clutch-pin 66 cannot be withdrawn by manipulation of the fingerping the machine or interrupting the formation of stitches. The seam produced by the machine under these circumstances comprises a continuous upper or needle-thread 96 formed as usual into a series of. loops--91 which penetrate the between substance or material 98 and are keyed by the under or looper thread loops 99 each of which is entered by the next subsequent needlethread loop 91.

The points I88 of periodical interruption of the looper-thread are so contrived that the last needle-thread loop 91 and looper thread loop 99 prior to each of the points I88 of interruption are keyed by the finishing end I8I of looperthread, so -that the seam is locked by the ends I8I of the interrupted looper-thread against ready ravelling.

Should ravelling of the looper-thread occur,

for any cause, it may only continue back to a point of interruption of the looper-thread and thus the entire seam is'safeguardedagainst being ravelled out.- In the present machine, the looperdesired by re-design of the cam 51 and wormdrive mechanism 58, 62.

The machine is equipped with a suitable workfeeding mechanism. Such feeding mechanism is shown and described in my copending applica tion, Serial No. 196,642, filed herewith and entitled Sewing machine feeding mechanism. The

feeding mechanism includes the feed-bar ,f pivotally connected at its forward end to the upper end of the rocker-arm f on the feed rock-shaft f to which is, fixed the crank-arm I connected by the pitman f to the feed-advance eccentric on the shaft 28. The eccentric 33 on the shaft 28 is connected by the pitman f to the feed-bar j to impart rising and falling components of motion thereto. The feed-bar has mounted on its overhanging free end the feed-dog I which has a clearance hole I in one side wall I for admission of the thread-cutter blade 45 which cooperates with the ledger-blade 4| located directly in front of the short center row I of feeddog teeth and between the two spaced side-rows I of teeth.

The looper-thread controlling means comprise three independent spring-arms I82, I83, I84 having their spiral spring-shanks I coiled about individual sleeves I85 on the arbor-pin I86, Fig. 2, fixed in the bed I by the set-screw I86. The free ends I8I of the spring-shanks are anchored in suitable slots I88 in the heads I89 of the sleeves I85 which heads I89 carry set-screws adjustably fixing them to the pin I86. The spring-arm I82, which is the take-up arm, is actuated by the eccentric II8 on the shaft I9 and plays vertically in the slot III formed transversely of the block II2 fixed in the bed I. The block II2 also has a thread-guiding slot II3 extending longitudinally thereof and crossing the transverse slot III. The looper-thread is placed in the slot II3 under the arms I82, I83, I84. The up-and-down motion of the take-up arm controls the slack in the looper-thread; paying out looper-thread to the looper as the latter advances to seize a needle-loop and moves to the extreme of its loop-seizing stroke. The takeup arm I82 also takes up the slack in the looperthread as the looper retracts from its extreme advanced position to shed the needle-loop. -The arm I83, which is operated by the eccentric. I83, cooperates with the fixed anvil 4 to clamp the looper-thread during. the slack-absorbing action of the take-up arm I83 on the retracting stroke of the looper. The arm I84, operated by the camor eccentric I84, pulls looper-thread from the supply and later pays it out to the looper through the open nipper I83, II4 during the latter part of the advancing stroke of. the looper.

The tension of the coil-spring ends I85 of the arms I82, I83, I84 may be adjusted by rotatively adjusting the respective sleeves I85 on the pin I86. The arms I82, I83, I84-are so light in weight that they will easily and quietly follow their actuating eccentrics at speeds of 9080 stitches per minute, at which the present machine has actually been successfully operated.

The block 2 is formed with a seat II5, Fig;

passes. A spring I I8 coiled about the stud H9 and backed by the adjusting nut I28 presses the plate I" yieldingly uponthe looper-thread running between the base-plate I I6 and the tensionplate I.

The invention is not to be understood as limited to the specific forms and arrangements of parts herein shown and described as illustrativeof the invention. Various modifications may obviously be made by those skilled in the art within the spirit and scope of the invention.

Having thus set forth the nature of the in- 5 vention, what I claim herein is:

1. A sewing machine having a frame including a bed, a hollow standard rising from said bed, a bracket-arm, carried by said standard and overhanging said bed, top and bottom shaftsjournaled in said bracket-arm and bed, respectively, a main shaft journaled in said standard between the levels of the top and bottom shafts, a powerreceiving belt-pulley fast on the main-shaft within said standard, driving connections within said standard between said main-shaft and the top and bottom shafts, and a balance-wheel on said main-shaft outside of said standard.

2. A sewing machine having a frame including a bed, standard and overhanging bracketarm, three parallel rotary shafts the top one of which is journaled in said bracket-arm and the bottom two of which are journaled in-said bed, a main-shaft journaled in said standard and belt connected to drive said three parallel shafts at twice the speed of said main-shaft, a reciprocatory needle actuated by the top shaft, a thread-' carrying chain-stitch looper actuated by one of said bottom shafts, and a looper-thread cutter,

actuated by the other bottom shaft.

having an actuating shaft, an eccentric thereon, .a lever having between its ends a follower portion embracing said eccentric, means to support one end of said lever for movement in a direcpivotally mounted adjacent the other end of said lever to rock on an axis parallel to the axis of said shaft, a link connected to transmit the endwise movement of said lever to said looper-.

carrier, a looper having a shank pivotally mounted in said looper-carrier, and means connected to said lever for oscillating said looper upon and relative to said looper-carrier.

4. In a sewing machine, a looper having a shank formed with a pivot hole and an actuating hole adjacent thereto, a looper-carrier, a pivot-pin passing through said pivot hole and mounted in said looper-carrier, means to rockably support said looper-ecarrier on an axis transverse to the lever having an actuating pin entering said actuating hole.

5. In a sewing machine, a looper having a shank formed with a pivot-hole and an actuating hole adjacent thereto, a looper-carrier, a pivot-pin passing through said pivot-hole and mounted in said looper-carrier, means to rockably support said looper-carrier on an axis transverse to the axis of saidpivot-pin, an eccentricactuated lever having an actuating pin entering said actuating hole, and a link-connection with said looper-carrier.

6. A looper mechanism for sewing machines comprising, a shaft carrying an eccentric, a lever actuated by said eccentric, a support for one end of said lever, a pivotally mounted loopercarrier, a link-connection between said lever and looper-carrier, and a looper pivotally mounted in said looper-carrier and operatively engaged by sai q lever.

:9 mechanism for sewing machines ollower embracing said eccentric, a thin plate-like'lever carrying said cylindrical foltlower with'the plane of said, lever'transverse to 3. 'A looper mechanism for sewing machi'nes tion toward and from said shaft, a looper-carrier ing connections axis of said pivot-pin, and an eccentric-actuated g a shaft carrying an eccentric, a cythe axis of said follower, a support for one end of said lever, a pivotally mounted looper-carrier, a link-connection between said lever and loopercarrier, and a looper pivotally mounted in said looper-carrier and operatively engaged by the free end of said lever.

8. In a sewing machine, the combination with a reciprocatory thread-carrying needle and complementary under thread mechanism, of means to periodically sever the under thread only'without interruption of the stitching function of the machine.

9. In a sewing machine, the combination with a reciprocatory thread-carrying needle and a complementary thread-carrying chain-stitch looper, of means to periodically sever the looperthread only, without interruption of the stitching functions of the needle and looper.

10. ha sewing machine, the combination with a thread-carrying reciprocatory needle and a thread-carrying looper-blade with means to move the -looperblade endwise into and out of the needle-thread loops and laterally of itself to carry the looper-blade from one side of the needle to the opposite side thereof, of a thread-cutter blade having a pilot-nose and a cutting edge, means to move the pilot-nose of the thread-cutter into a looper-thread loop after the latter has been projected, through a needle-thread loop, and means to further move the thread-cutter to sever the looper-thread after the looper has taken the next thread-loop from-the needle.

--11. In a sewing machine, the combination with a thread-carrying reci'procatory needle and a complementary thread-carrying looper, of a looper-thread cutting implement, a drive-shaft running with the machine, a cam for actuating said thread-cutting implement and manually controlled means to establish and interrupt drivbetween said drive-shaft and said'cam.

12. In a sewing machine, the combination with .a thread-carrying reciprocatory needle and a 13. In a sewing machine,- the combination witha thread-carrying reciprocatory needle and a thread-carrying'looper with means to move the looper endwise into and out of the needle-thread loops and laterally of itself to carry the looper from one side of the needle to the opposite side thereof, of a thread-cutter having a pilot-nose and a cutting edge, means to move the thread cutter horizontally over the looper in the direction of feed of the work to carry the pilotnose into the looper-thread loop projected through a needle-thread loop, and means to further move the thread-cutter to severthe looperthread after the looper has taken :the next needle-thread loop.

ing upon said eccentrics and having their shanks anchored to and spirally wound to embrace said arbor, and a looper-thread guiding block having a longitudinal thread-guiding slot and transverse clearance slots into which said arms, extend, one of said clearance slots having a bottom wall arranged to coact with its respective arm to periodicallynip the looper-thread.

l5. Looper-thread controlling mechanism comprising a shaft having a plurality of eccentrics thereon, an arbor parallel to and spaced from said shaft, a plurality of spring wire arms hearing upon said eccentrics and having their shanks anchored to and spirally wound to embrace said arbor, a looper-thread guiding block having a longitudinal thread-guiding slot and transverse ing means associated with the portion of said n wire beyond said eccentric.

1'7. Looper-thread controlling means for sewing machines comprising a thread-guiding block having a thread-guiding groove cut longitudinally thereof and a plurality of clearance grooves cut transversely thereof and intersecting the thread-guiding groove, a plurality of thread-controlling members playing in said transversely out grooves, and means to actuate said thread-controlling members.

l8. Lo'oper-thread controlling means for sewing machines comprising a thread-guiding block having a thread-guiding groove cut longitudinally thereof and a plurality of clearance grooves cut transversely thereof and intersecting the thread-guiding groove, a plurality of thread-controlling members playing in said transversely cut.

grooves, means to actuate said thread-controlling members, and a manually adiustable springpressed thread-tension device mounted on said block and including'anpair of tension-plates the dividing plane between which is substantially coincident with the plane of the thread-guiding groove in said block.

19. In a sewing machine, a reciprooatory needle, a complementai looper, a feed-bar, a rotary shaft having an eccentric thereon, and means actuated by saideccentrio to impart rising and falling movementsto said feed-bar and loopseizing-and-shedding and needle-avoiding movernents to said looper.

20. The combination with a reciprooatory needle, a thread-carrying looper, and work-feeding mechanism including a feed-dog having spaced side rows of teeth, of a ledger-blade stationarily mounted between said rows of teeth,

and a. looper-thread cutter blade cooperatively related to said ledger-blade.

21. Ina sewing machine, the combination with a feed-dog having an apertured side-wall and spaced side rows of teeth, of a ledger-blade mounted independently of said feed-dog and disposed between said side rows ofteeth, and a thread-cutter blade mounted at one side of said feed-dog and extending through the apertured side-wall of said feed-dog into cooperative relation with said ledger-blade.

-22. The combination with stitch-forming mechanism comprising a reciprooatory needle and a complementary thread-carrying chainstitch looper, of means to enter and detain a loop of looper-thread while the needle and looper continue their cooperative stitch-forming functions, and means to sever the detained loop of looper-thread.

23. The combination with work-feeding mechanism andstltch-forming mechanism comprising a reciprooatory needle and a complementary thread-carrying chain-stitch looper, of means to enter and detain aloop of looper-thread while the feeding and stitch-forming mechanisms continue their work-feeding and stitch-forming functions, and means to sever the detained loop of looper-thread after the work has been fed at least one stitch-length subsequently to the detention of said looper-thread loop.

ALBERT H. DE VOE. 

